Wind and Solar Based Energy Systems for Communities

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A sustainable community energy system is an approach to supplying a local community - ranging from a few homes or farms to entire cities - with its energy requirements from renewable energy or high-efficiency co-generation energy sources. Such systems are frequently based on wind power, solar power, biomass, either singly or in combination. Community energy projects have been growing in numbers in several key regions.This book provides an overview of existing and emerging community energy technologies. Topics covered include data-driven methods for prediction of small to medium wind turbines performance; optimization of wind farms for communities; financing for community wind and photovoltaic project development; community-level solar thermal systems; solar water desalination for small communities; community solar photovoltaic projects; assessing wind loads for urban photovoltaic installations; design optimization of multi-energy hubs for community energy projects; battery based storage for communities; power-to-gas and power-to-power for storage and ancillary services in urban areas; smart multi-energy microgrids; and conservation and demand management in community energy systems. Wind and Solar Based Energy Systems for Communities is essential reading for researchers and engineers working to develop community energy systems and advance the transition to a clean energy future.

This chapter introduces the introduction of wind and solar energy for communities. According to dictionary.com, a community is a social group of any size whose members dwell in a specific locality under one government, and they share the same cultural and historical heritage. Accordingly, both big cities and small towns are communities. Their future leans on, among other things, the proper management of sustainable energy and natural resources that they feed. For the more progressive localities, there is already in place some solid share of renewable energy; wind, in particular. Other than the promise of including a greater extent of solar, these wind-fed communities must look at ways to further their current and future wind. To improve performance and maintenance of the existing, particularly wind, infrastructure alone would render significant stability in the community, renewable energy systems.

The growth in the wind energy is rapidly increasing. Accurate modelling of wind turbines performance as targeted by ongoing research studies can escalate wind energy production capabilities, reliability, and expand its potential to replace fossil fuels. In addition, optimisation of turbines will considerably expand the profit margins and garner the attraction of investors.

Energy supplies are moving away from environmentally damaging, finite, and expensive fossil fuels to renewable energy resources through technological innovations. Wind energy is one of the most advanced renewable energy resources due to the extensive research that has been ongoing over the last decades to optimize aerodynamic performance of wind turbines, structural design of wind turbines, control strategies, site selection, and the layout of wind farms. This chapter outlines fundamental elements of wind-farm-layout optimization including optimization parameters, objective functions, wake loss models, and search methods. Optimization parameters include base location, number, rotor diameter, hub height, rotational direction, and yaw angle of wind turbines, as well as shape of wind farm area. In the wake loss models section, all existing wake-loss models including large eddy simulation, nonlinear and linearized Reynolds-averaged Navier-Stokes models, stochastic models, kinematic models, and empirical models are discussed. In addition, different search methods, from simple greedy search algorithms to advanced genetic algorithms (GAs), are briefly reviewed and compared.

Community energy, and in particular, community wind and solar, has experienced significant growth in recent years. The main challenge to further expansion and implementation of community renewable energy projects is the high capital costs associated with project development. This chapter will present case studies of community wind and solar financing and include innovative mechanisms such as lease financing, sales of renewable energy credits, crowdfunding, and unconventional loan strategies. Through compilation of these cases, the objective is to provide prospective small renewable energy developers options as to how they can go about financing their projects and ultimately empower communities to independently produce energy while reducing greenhouse gases. Community energy, in particular, community wind and solar, has experienced significant growth in recent years. Driving this trend is the desire for communities to become energy self-sufficient and more environmentally conscious. Benefits of community wind and solar extend to include increasing community capacity, empowering residents, and promoting energy efficiency and conservation. The main challenge for further expansion and implementation of community renewable energy projects is the high capital costs associated with project development. With initial costs representing approximately 70 percent of the life cycle costs of the project [1], it can take several years to recoup this investment and can impede the ability of local developers to raise enough capital. Small utility-scale wind power projects have provided proving grounds for new technology and innovative financing structures. Historically, financing of community wind projects has generated innovative structures that were later adopted by the broader wind market and are now popular mainstream financing structures, such as the special allocation partnership flip structure [2]. More recently, community wind projects have been financed with creative structures that capitalize on incentives and make use of public market capital. Community solar is a popular community energy choice due to the scalability of projects. Small communities and neighbourhoods can pursue solar energy more easily by selecting the number of panels required to suit their needs. Community solar has relied on three main financing structures: utility-sponsored, special-purpose entity, and non-profit, to implement projects of various scales and make use of available incentives. Despite many community wind and solar projects achieving financing success, there are challenges in replicating the elements of some of these deals. Some of the cases only work in the exact circumstance presented due to specific incentive availability or legalities in different areas. Also, since these proposed structures are new to the industry, transaction costs may be high due to the learning process of executing these deals and development of the financing package could be lengthy for the same reason. This chapter will present case studies of community wind and solar financing and include innovative mechanisms such as lease financing, sales of renewable energy credits, crowdfunding, and unconventional loan strategies. Through compilation of these cases, the objective is to provide prospective small renewable energy developers options as to how they can go about financing their projects and ultimately empower communities to independently produce energy while reducing greenhouse gases. These examples serve as encouraging case studies for other community projects looking for ways to raise capital and make use of programmes and incentives to piece together a financial package. Furthermore, the cases presented have the potential to extend beyond community projects to commercially renewable energy project finance.

This chapter provides a brief background in the various conventional methods (surface-based absorption of solar energy) available for harnessing solar thermal energy at a community level. It describes some of the main differences between the typical non-concentrating as well as concentrating type solar collectors, and highlights some of their main attributes. It also presents in detail the results of a novel technique for harnessing solar energy. In this technique, the solar energy is directly absorbed by the fluid (volumetrically) using nanoparticle-laden fluids (hence, it is categorized as volumetric-based absorption of solar energy). Such a collector is analysed in detail using a numerical model. The results of the numerical model are then discussed, which simulates the requirements of hot water for a typical community consists of about 10 households (40 persons). Two of the main performance evaluation parameters - collector efficiency and the fluid outlet temperature - have been extensively studied, and the influence of various design and operational parameters (particle volume fraction, mass flow rate, solar irradiation, collector height, collector length) on these two have been studied in detail. Moreover, the variation of spectral intensity, energy generation rate and spatial temperature distribution within the collector has been quantified. The calculations also show the dimensions of the desired solar collector in order to meet the daily hot water requirements (100 kg/person) for this community.

The use of solar-water desalination is one of the most promising and environment friendly means to meet the ever-increasing demand of fresh water in freshwater-scarce communities. Unfortunately, desalination of water is a highly energy-intensive process. Nonetheless, direct solar-water desalination is simple in design, low in cost, and can easily support the daily use of communities. This chapter describes various types of solar-water desalination with a focus on technologies that are suitable for small communities and remote areas. Mathematical modeling of direct solar-water desalination based on convective, radiative, and evaporative heat transfer has been provided. A case study from Pasni, District Gwadar, Balochistan of Pakistan involving design, fabrication, and cost is included to give an overview of the practical operation of technology.

In today's world, global warming (GW) and the resulting climate change are a significant threat to humans, plants and animals. The main contributor to GW is greenhouse gases (GHGs) that are created from the burning of fossil fuels, mainly for electrical power. Hence, the way forward in safeguarding the future of life on planet earth is to reduce on our GHG emissions and move rapidly to the utilization of renewable energy resources that are abundantly available. There are numerous advantages in implementing renewable energy projects versus the use of fossil fuels in meeting individual or community energy demands. With renewable energy, an individual or community will be able to have a more diverse and stable long-term energy supply, considering fossil fuel resources are slowly being depleted. Small-scale renewable energy projects, especially in remote communities which are currently served by diesel-generated electricity, offset the community's use of diesel fuel. Although there will be times when renewable energy is not available and a back-up source of power is required, the long-term cost of energy may be reduced. And the use of indigenous energy can contribute to a nation (or region's) energy security by significantly reducing its dependence on imported oil (assuming it is not an oil exporter). There are numerous renewable energy resources available globally (wind, solar, biomass, falling water, geothermal) that can be used for individual or community energy projects. Community energy projects are distinguished from other renewable energy projects in which members of the community are subscribers who use the electricity produced by the project, even though each individual does not solely own the equipment. This chapter presents an overview of how energy captured from the sun can be utilized at the community level by installing solar photovoltaic systems in the form of a solar garden or solar farm or solar power plant to generate electrical energy in meeting some, if not all, of the community total energy demand. In addition, readers will be exposed to three common ownership models and their benefits, barriers affecting the adoption of such projects and selected examples of such projects that have been completed or are in the conceptualization or construction phase within North America, Europe, South America and East Africa.

Rooftop solar photovoltaic installations are becoming common around the world but knowledge of the wind loads on them is not as advanced. The wind loads are important as they determine the cost of the structure needed to hold the photovoltaic modules in place, which can be a significant proportion of the total project cost. This chapter discusses these wind loads and reviews the few international building codes that cover them. Wind loads can be estimated from wind tunnel tests on model installations or by computational fluid dynamics simulations. We show that there are problems with both methods, due largely to scaling issues for the former and limitations in turbulence modeling for the latter. Wind tunnel tests show significant scatter in module pressures but improvements in test methodologies is likely to reduce these in the future. Future full scale rooftop measurements are also likely to improve our knowledge.

In this chapter, the authors study the effect of accounting for the hourly emission factors on the optimal primary energy consumption, natural gas, and electricity, for a network of energy hubs. Each hub is representative of a part of an urban area such as a school, residential complex, or hospital, in Ontario. In order to accomplish this, a mathematical model is developed based on two objectives, reducing the total annual cost of the system and the greenhouse gas emissions. Different technologies such as combined heat and power systems, solar photovoltaics, solar-thermal collectors, boilers, and heat and electrical storage systems are considered. Different scenarios are defined to investigate the effect of energy storage systems and energy exchange between buildings on the optimal configuration of the system. The results are compared for different scenarios based on total annual cost, CO2 emission, as well as natural gas and electricity consumption for constant and hourly emission factors.

Instantaneous load demand variations and fluctuations introduced by renewable energy sources (RESs) to the system, pose various challenges to the operation of the grid. Significant support to the grid can be provided by energy storage systems (ESSs) strategically placed and sized. In the presence of ESSs combined with RESs proximate to load centres, transmission losses are minimized and grid infrastructure upgrades are deferred, due to local generation and consumption of electric energy. This is without the need to transfer energy from remote power plants. Furthermore, ESSs introduce considerable flexibility to electric energy, which can now be consumed when it is needed the most (e.g. during the on-peak period). As a result, the loading levels of the grid components are reduced and the terminal voltages are maintained within the allowable limits. This chapter presents an in-depth study of battery storage for communities and an analysis of major battery-storage technology and application. This includes another special form of distributed energy storage - the electric vehicle.

In this study, power-to-gas, whereby hydrogen is generated electrolytically, and power-to-power, whereby electricity is used to produce hydrogen which is used, in turn, to generate electricity at a later time, are examined for their efficiency and emissions reductions in providing energy storage and ancillary services. Due to a large baseload of nuclear energy in the province of Ontario, and with wind generation added to the grid prior to 2014, the supply of electricity exceeds demand at certain times of the year during off-peak hours. To manage this excess supply, electricity is exported to neighboring provinces and states at a low, often negative price, due to the decreased demand and surplus generation. To curb these exports, the Independent Electricity System Operator (IESO) has switched renewable generators from nondispatchable to dispatchable energy sources that can be turned on or off or adjusted to output a different quantity of energy. In addition, due to the large baseload, the IESO has also shifted to allowing loads to offer demand response services previously only offered by generators. In this analysis, the rapid response of polymer electrolyte membrane electrolyzers, used to generate hydrogen in power-to-gas and power-to-power systems is also able to offer important and high value auxiliary and regulatory power services. In power-to-gas systems, the hydrogen produced is an alternative energy vector which can be contained within the natural gas infrastructure or other storage medium. For this analysis, the authors employ the General Algebraic Modeling Simulation to develop a simulation of a 2-MW power-to-gas and power-to-power system that produces hydrogen for energy storage and then uses this hydrogen to generate electricity when there is a peak in energy demand. This energy is then reintroduced into the electrical grid using a hydrogen turbine. The power-to-power scheme, although typically less energy efficient, provides the flexibility to meet changing energy demands while generating hydrogen that can be used for industrial purposes and as a transportation fuel.

It is trite to say that more needs to be done to save our environment. And the shift from fossil fuel to renewable energy sources is an essential move. This shift implies changes in the electricity sector, and also in the two main greenhouse gas producers - transport and heating. These changes alone will not work, unless the electricity powering them is produced from clean energy sources. Fine-tuning the interplay, between the variable and uncertain production and the flexibility via advanced control of demand, is the key in making a transition to a low-carbon society.

Community Energy Systems (CESs) are localized systems that can generate, deliver, and/or store energy, which can come in different forms, including electricity, natural gas, and district heating. These can be operated in islanded mode or tied into the main grid, either continually or for backup purposes. Since CESs are by definition small-scale, even small deviations from forecasts can be much more costly to users as those costs of overbuilding or underbuilding are shared among a much smaller group of consumers (rather than the much larger pool across the larger system). Accurate peak load forecasts are very difficult, and they are especially difficult for CESs because inaccuracies cannot be smoothed across a larger base. Conservation and demand management can be efficient tools to smooth over inevitable deviations from forecasts. The conservation model proposed in this chapter would target conservation at the most elastic (price sensitive) consumers only during narrowly defined peak periods in order to increase utilization of fixed assets and drive down unit costs. This would reduce the overall capacity requirements of the system, and these savings would be saved among all users. The three main elements of this model are to (1) lower the peak in order to defer capacity expansions; (2) increase utilization in order to reduce unit costs and rates; and (3) target conservation efforts at the most elastic (price sensitive) consumers so that conservation is procured at the lowest possible cost. Conservation can be achieved through a combination of disincentives for consumption during very narrow peak periods and incentives for consumption during off-peak periods. Together, these have the effect of flattening the demand curve.